20 February 2008

Global Seminars & Invited Speaker Series

DECORATIVE ARTS AND ARTISTIC TECHNIQUES

Glazes: theory and techniques

Dr. María Luisa Martín Ansón.
Autonomous University of Madrid

Throughout the history of art, the techniques of enameling on metal have enjoyed unequal esteem according to the times. Intimately linked to the development of goldsmithing, sometimes they appear subordinate to it and others acquire the category of independent art. They are applied on various metals, the most important being gold, silver and copper, the latter usually over-gilded.

Enamel is a glass reduced to powder and colored by metallic oxides: iron (red); antimony, lead and silver (yellow); cobalt (blue); copper (green), etc. These oxides generally leave it transparent but sometimes make it opaque. It is applied on different substrates, especially metal sheets coated with flux (subject colorless glassy) to facilitate adhesion. The back of the plate is covered with counter enamel to prevent expansion causing deformation. Its melting temperature is between 700º and 850º.

"Little horse of Altötting". Enamel in round bulge. Beginning of the 15th century

The techniques used for the incorporation of the enamel to the metal are diverse. The procedure of the alveolate orcloisonné is described in detail, at the end of the XII century, by the monk Theophilus, in his treatise Schedula Diversarum Artium or De Diversis Artibus. It is basically applied on gold and silver.

The digging orchamplevé (champlevé) is a Western system whose use dates back to the Second Iron Age. Philostratus of Lemnos (court of Emperor Severus, beginning of the 3rd century) testifies how "The Barbarians, inhabitants of the Ocean spread colors on the burning copper, which once cooled become a hard enamel like stone". Its use disappears almost completely in the Europe of the Invasions and will be the usual procedure of the Romanesque world. The metal used is usually copper that is overgilded to maintain the brightness of gold.

The enamel on relief(basse-taille) is applied on silver or gold, replacing the opaque enamel by the translucent one. The change occurs at the end of the 13th century in Italy and covers the Gothic period.
The plique-à-jour enamel, or fenestrated technique, is a variant of honeycomb enameling used mainly between the 14th and 16th centuries.

The enamel on rounded bulge (Ronde Bosse) requires the application of colors to the sculpture. It developed especially at the end of the 14th century and the beginning of the 15th century.

The enamel painting became very popular from the XV century until the XVII-XVIII centuries. Used on copper, it reached its peak in Limoges to the point of being known generically as "Limousin enamel", creating real dynasties of enamel painters. Variants of this technique are the grisaille and the employment of"paillons".

In enamel painting, which became widespread from the 17th century onwards, the main instrument is the brush, so that the enameller acts as a painter. This technique began timidly in Limoges but developed rapidly and with great success in Geneva, where a school of enamel painters was formed. The most important figure was Jean Petitot (1607-1691). The second half of the 18th century and part of the 19th century will be the time of the miniature on enamel but without continuation in the following years. 

However, since the mid-nineteenth century there were numerous attempts to recover the various techniques of enameling, within a context of revaluation of the medieval and Renaissance world that led to the creation, among others, a section of enamels in the manufacture of Sevres, under the direction of Meyer-Heine. From this point on, we witnessed a new wave of important artists, with Claudio Popelin standing out, as well as an increase in fraud in the market.
 

"Royal Cup" (also called "Cup of Saint Agnes"). Translucent enamel on gold. XIV Century